Abstract: To clarify the low‑temperature stress response mechanisms of tea plants at different altitudes，we studied the Xinyang group species in the Shihe District of Xinyang City，Henan Province，at altitudes of 100 m and 600 m. We analyzed the photosynthetic characteristics，antioxidant enzyme activities，membrane lipid peroxidation levels，and tissue cell structure changes of tea leaves during the overwintering period. Results showed that during the pre‑winter（T1），mid‑winter（T2），and late‑winter（T3）stages，the net photosynthetic rate of low‑altitude tea plants was 0.6，1.5，and 1.2 times higher than that of high‑altitude tea plants，respectively. Chlorophyll content in low‑altitude plants was 36.91% and 48.19% higher than in high‑altitude plants during T2 and T3.Low‑altitude plants also exhibited more intact chloroplast structures.Throughout the overwintering period，superoxide dismutase（SOD）activity in leaves of tea plants at both altitudes first increased and then decreased，peaking in T2.During T1，T2，and T3，SOD activity in high‑altitude tea leaves was 25.20%，27.05%，and 20.59% higher than in low‑altitude tea leaves，respectively.However，catalase（CAT）activity in high‑altitude tea leaves was 27.27%，29.48%，and 26.64% lower than in low‑altitude leaves. Peroxidase（POD）activity showed a trend similar to that of CAT activity.The malondialdehyde（MDA）content of high‑altitude plants in T2 and T3 was significantly higher than that of low‑altitude plants，increasing by 72.21% and 77.04%，respectively.Structural observations revealed that the mesophyll thickness of high‑altitude tea plants increased significantly in T2 and T3，rising by 10.19% and 10.47% compared to T1.The stomatal opening rate and open area of high‑altitude plants decreased significantly in T2.Compared between the two altitudes，low‑altitude tea leaves had higher cell wall thickness and stomatal density，averaging 36.92% and 22.52% higher than high‑altitude tea leaves，respectively.In conclusion，low‑altitude tea plants adapt to low‑temperature environments by maintaining high photosynthetic efficiency and antioxidant capacity，as well as by enhancing cell wall and stomatal structures.In contrast，high‑altitude tea plants optimize water management by increasing mesophyll thickness and adjusting stomatal opening，although this may come at the cost of reduced photosynthetic efficiency.

Key words: Tea plant, Leaf, Altitude, Overwintering stage, Physiological characteristics, Cellular structure

摘要： 为探明不同海拔条件下茶树对低温胁迫的响应机制，以河南省信阳市浉河区不同海拔（100 m和 600 m）信阳群体种茶树为研究对象，分析了茶树在越冬期间的光合特性、抗氧化酶活性、膜脂过氧化情况以及组织细胞结构的变化。结果表明，低海拔茶树的净光合速率在茶树越冬前、中、后期（分别表示为T1、T2、T3）分别比高海拔茶树高出0.6、1.5、1.2倍，叶绿素含量在T2和T3时期分别比高海拔茶树高出36.91% 和48.19%，且叶绿体结构更为完整。在整个越冬期间，不同海拔茶树叶片超氧化物歧化酶（SOD）活性均呈先升高后降低的趋势，T2时期显著高于T1和T3时期；T1、T2和T3时期高海拔茶树叶片SOD活性分别比低海拔茶树高25.20%、27.05%和20.59%，而过氧化氢酶（CAT）活性则分别较低海拔茶树降低27.27%、29.48%和26.64%，过氧化物酶（POD）活性变化与CAT活性变化趋势基本一致。高海拔茶树的丙二醛（MDA）含量在越冬中后期（T2、T3）显著高于低海拔茶树，分别增加72.21%和77.04%。组织结构观察发现，高海拔茶树的叶肉厚度在越冬中后期显著增加，T2和T3时期分别较T1时期增加10.19%和10.47%，而其气孔开放率和开放面积在越冬中期（T2）显著降低。不同海拔茶树比较，低海拔茶树叶片的细胞壁厚度和气孔密度更高，分别较高海拔茶树平均提高36.92%、22.52%。综上所述，低海拔茶树通过维持较高的光合效率和抗氧化能力、增强细胞壁和气孔结构来适应低温环境，而高海拔茶树则通过增加叶肉组织厚度和调节气孔开放程度来优化水分管理，这可能以牺牲光合作用效率为代价。

关键词: 茶树, 叶片, 海拔, 越冬期, 生理特性, 细胞结构